614 SUMMARY OF CURRENT RESEARCHES RELATING TO 



follows : — In a small number of species there can be no question of the 

 existence of pores ; while in a very large number of species their exist- 

 ence is very probable. In some species of Pinnularia the non-existence 

 of pores has been made very probable by M tiller and Lauterborn ; and 

 the same is regarded by Mtiller as also probable in a small number of 

 species belonging to other genera. In a somewhat larger number of 

 species, especially in those with imperfect raphe, observations have not 

 . at present been sufficiently exaut to determine the question. Negative 

 evidence on the question cannot at present be regarded as conclusive. 



The author regards it as probable that perforation of the valve was 

 characteristic of the archaic type of diatoms. One of the most highly 

 developed types is probably that of the Pinnulariere, in which the 

 numerous small pores of the original type have been replaced by a 

 highly developed raphe. 



If these conclusions are correct, they are regarded by Schtitt as to a 

 large extent negativing the supposed isolation of diatoms from all other 

 forms of vegetable life. Prom the diatom genus Melosira it is but a 

 step to Hyalotheca among DesmidiaceaBj and to Exuviella among Peri- 

 dinieaa ; and these three families may be grouped together as constituting 

 the class Placophyta or Placophyceae. 



Synedra hyalina sp. n., a new non-chlorophyllous Diatom.* — Dr. S. 

 Provasek has found, on decaying masses of Ulva at Trieste, an addition 

 to the very few recorded instances of a diatom destitute of chlorophyll. 

 Synedra hyalina sp. n. is a minute organism, about 0*04 X - 0034 mm., 

 endowed with rapid motion ; the valves have no fine sculpture. The 

 hyaline protoplasm forms, in the middle of the cell, a biconvex bridge, 

 from which a delicate layer of protoplasm runs along the two valves 

 towards the poles; in the poles is a mass of protoplasm; the inter- 

 mediate cavity may, or may not, be traversed by lainelbe of protoplasm ; 

 it has a roundish nucleus ; there are no leucoplasts. The discovery is 

 of interest in connection with a possible derivation of the Diatomaceae 

 from the Flagellata. 



Fungi. 



Rhizomucor parasiticus, a new pathogenous Fungus.f — In the 

 bronchial tubes of a woman about thirty years of age, living in the 

 country, MM. Lucet and Costantin found a fungus which was distinctly 

 parasitic and pathogenous, causing cough and other morbid conditions. 

 It belonged to the Mucorini, and is named by its discoverers Rhizomucor 

 parasiticus sp. n. It constitutes a new section of the genus, characterised 

 by irregular stolons and rhizoids and branched sporangiophores ; the 

 columel is surrounded at the base by the debris of the membrane of the 

 sporange. It was found to be pathogenous to rabbits and guinea-pigs ; 

 but with dogs the results were negative. 



Structure of the Protoplasm of Mortierella.J — By the use of the 

 pigment (violacein) derived from chromogenous bacteria (see p. 647) 

 M. L. Matruchot has detected what he terms a "canalicular" structure 

 in the protoplasm of the unseptated hyphaa of Mortierella reticulata. At 



* Oesterr. Bot. Zeitschr.. 1. (1900) pp. 69-73 (2 figs.). 



t Rev. Gen. de Bot. (Bonnier), xii. (1900) pp. 82-98 (2 pis.). 



X Tom. cU., pp. 33-60. 



